Gearing



March 19, 1935.

R. BlSHOP GEARING Filed April la, 1934 2 Sheets-Sheet 1 W6( @raf/2f fw? @@@M/V R. BISHOP GEARING March 19, 1935,

Filed April 18, 1934 2 Sheets-'Sheet 2 Patented Mar. 19, 1935 UNITED sm'reis'k PATE NTv `OFI-"ICE y GEARING Reginald Bishop,

Golders Green, London, England Application April 18; 1934, serial No. 721,200

In Great Britain July 10, 1933 f f eoiaims. v. (01.74-11.58)

vThis invention relates to gearing that is particularly, though not exclusively, applicable to thesteering 4of mechanically propelled `vroad vehicles, which gearing is of the kind (hereinafter referred to as the kind speciiied) that comprises a cam which is engaged by a follower mounted on a rocker-arm that is angularly movable parallel to the side-of the cam, the said rocker-arm being mounted on a rocker-shaft.

In gearing of the kind speciiied which I have previously invented the cam is in the form of a worm thread of constant diameter but not a true helix, the follower is a pin or roller, the rockerarm is movable in a plane parallel to the longitudinal axis of the cam, and the axes of the rockerarm and of the follower are at rightangles. Other gearing of the kind specified also invented by me is generally similar to that just described except that the follower. is in the form of an elongated shoe. f

It is an object of the invention to cause the follower to rock in a predetermined manner on its pivot during rotation of the cam and thereby to avoid or minimize bindingaction between said cam and follower.

One feature of the invention is gearing of the kind speoied having means to move the follower about its axis by predetermined amounts in accordance with the Vmovement of the followercarrying arm about the axis of the rocker-shaft.

The invention will become more fully apparent from the following description, in conjunction with the accompanying diagrammatic drawings, of one construction of gearing according to the invention.

In the drawings,

Fig. l is a view in elevation, partly in section, of gearing according to the invention;

Fig. 2 is a viewin elevation, partly in section, at right angles to Fig. 1;

Fig. 3 is a diagram showing an alternative method of producing the desired movement;

Figs. 4 and 5 are diagrams indicating an alternative form of follower; and

Fig. 6 is a view similar to Fig. 2 of an alternative construction.

Referring to Figs. 1 and 2 the' worm or cam 11 of the gearing is of constant diameter and constant pitch. A follower 13 is in the form of a single elongated shoe which iits into the thread of the worm. This shoe 13 is, in this particular case, integral with a pivot-pin 15 of large di` ameter which is mounted for oscillation in a bearing 17 in the free end 19 of a rocker-arm 21 which .is fixed upon a rocker-shaft 23, the arrangement being such that the axis ofjthepivot-pin 15 is parallel with theyaxis of the rocker-shaft v23. The pivot-pin l5 is extended so as to pass right through the rocker-arm 21 andy on its rear end it is provided withvaf-crank-pin 25. Thiscrankpin 25 has pivoted on it a block 27- which is located and guided in an arcuatecam-slot 29 which is formedin a stationary member 3l which in this particular vc :onstruction forms the 'back wall 4-of the gear casing 33. vThe arcuate cam-slot 29 is of the samemean radius asv the effective vradius of the rocker-arm 21 and is struck about a centre- 35 (Fig.V 2) which is offset from `the axis 24 of the rocker-shaft 23 by the sameV amountthat thev axis of the Acrank-pin 25'is offset from the axis ofthe.pivot-pn 15. Thearrangement is such thatas the cam 1l rocks the rocker-arm 2l, the block 27 will befdriven along Vthe cam-slot 29 and will liftor lower the crank-pin 25 to rock the pivot pin 15, with the result that the follower 13 will be rocked in such a manner that in all positions thelongitudinal middle line of the follower will (in this particular, constructionlremain parallel to its original position.

The block 27 maybe in the form of a ring (or the block may be omitted and the pin be large enough to take its place) encircling `thecrank pin 25; this would give line'contact with thecam slot 29. It is preferred, however, to form the block 27 as an elongated arcuate slider (see Fig. 2), as this will give extended surface contact with thercam-slot 29 and so will induce more easy operation than is possible with line contact.

A somewhat similar result might be obtained by the use (instead of the crank-pin and camslot) of a radius arm 41, Fig. Y3, on the pivot-pin 15, a pin 42 on the casing eccentric to the axis of the rocker-shaft 23 by the same amount as the effective length of the radius arm 4l, and a link 43 connecting the pin 42 and the arm 41; the

40y radius arm might if desired be made adjustable 1 crossed belt wrapping fromsuch position vby predetermined amounts during its travel, the displacement being, for instance, proportional to the displacement ofv therocker-arm from its mid-position. This result fioI 5 shoe, for example a double shoe 13a, 13b (Figs.

4 and 5) with a groove betweenv the parts rso that the land of the cam worm would nt into the groove of the follower; In thiscase-the rocker- -arm 21 might be extended as at 21a intoadja'cent grooves of the cam worm 11 so as to embrace approximately the whole depth of the shoe'at'.; about its middle; thus the sidethrust and con.-A k sequent canting action 'on the Shoe would be ytaken directly by that portion ofA thejrocker-arm opposite the portion of the shoe receiving such thrust.

In a further alternative IEigiffi)thc-,fmfol-'j lower instead of being supported in the' "1oc1 e1 ^'V pin r15 'ofY the follower passes'lthrough this blockvv 27 and through the fixed member 53, .andhas fixed toit a rcrank` arm'55 having-Vac ,ranlt-pin` 5'?k which is .pivotedV in the-" upper` end ofl 'the rocker-arm 21.

What I claim,` isf-' er-arm `upon which said follower is? pivotally mounted, a rocker-shaft carrying the said"-'armin*` such manner that .the latter is angularly' mov-l able parallel-tothe side of the cam,"andcontrolmeans acting betvveeria fixed part of-thegearing and saidfollower and operative -forf impart-J1 ing positively to the latter arl-predetermined piv-- otal `movement dependent "upon the rocking movement of therocker-'arm- 2. Gearing comprising a "worm-like cam; al`

rocker-shaft, a rocker-arm carried by vsaid :rocker shaft, alpivot-pin ounted foroscillation in relation to the 'rocker-arm,an` `elongated fol? lower carried by the pivot-pin and'opei'atively engaging with the cam, Icrank means connectedto the pivot-pin for* "oscillationtherewith, and an operative connection between said crank means'and a xed part of the gearing; the 'saidl connection being adapted for imparting afposi tive oscillatory movement through the crank means to the pivot-pin-and follower as the rocker-arm is rocked.

3. Gearing comprising a xed body, a wormlike cam rotatable in relation to said body, a rocker-shaft, a rocker-arm carried by said rocker-shaft, a pivot-pin oscillatable in the rockerarm,I an elongated-follower carried bythe pivotpinand engaging with the-cam, a crank-pin also carried by the pivot-pin, an arcuate cam-slot 'formed in the fixed body and having the crank pinguided in it, the said cam-slot having a` mean radius equal to the effective radius of the rockerfarmandbeing strucl; about a centre that is (offset from the axis ofthe rocker-shaftby the f sameamOunt. that the crank-pin is offset from the.' axis 'of the pivot-pin.

4; Gearing "comprising a cam with a worm-like }land,"afo11ower having an elongated groove into which fits the land of, the cam, a rocker-arm upnwhich said follower is pivotally mounted; a

rocker-shaftarrying the said arm in such manner that the* latten is -angularly movable parallel i tothe sidegofv thejcam, and control means acting between afifedpartof the gearing and said f Afollowerand"operativefor imparting positively to c 1' -f theflat'ter a predetermined pivotal movement dev n 1. Gearing'r comprising' a c`am`, lang-elongated Y* W follower operativelyengaging'said cam-,"arocbf pendent'up'on-A the -rocking 'movement of the rocker-'arm.

, 5.* Gearing according -ftor' claim `it, `comprising .also arcuate cheeks embracing the` follower *andA .entendin'g from lvther-urcckerfarm ,into 'the grooves fbrmedhstween theipart A1 0f the @maand-err' gaged4 kythe ffollower-groove`- andjfthe parts of' *6: Gearing comprising axed body;arlactuat `ing element in the form' of a worm-like cam Arotatable in said. fixed body, an' elongated follower Aengaging said cam,v a rocker-arm, a pivotal mounting on said roclrzerarmforsaid follower',l an actuated elementin theA form of a rockershaftfc'arrying said' rocker-arm,` and an operatraverses the vwornfviv-lilre cam.`

` Y REGINALD BISHOP. 

